Previously, update notifications were always shown and auto-update was
always attempted. This change gives users control over both behaviors:

- showUpdateToasts (default: true) - Control whether update toasts appear
- autoUpdate (default: false) - Opt-in to automatic config version updates

With autoUpdate disabled (the new default), users are simply notified of
available updates without any config modifications. This is less intrusive
and gives users explicit control over when their config changes.